1. Field of the Invention
The invention relates to a method of a location service in a communication system, and more particularly, to a method for a mobile device to initiate a location service for obtaining multiple location information of another mobile device in a communication system.
2. Description of the Prior Art
Open Mobile Alliance (OMA) is the focal point for the development of mobile service enabler specifications, which support the creation of interoperable end-to-end mobile services. OMA drives service enabler architectures and open enabler interfaces that are independent of the underlying wireless networks and platforms. OMA also creates interoperable mobile data service enablers that work across devices, service providers, operators, networks, and geography. Toward that end, OMA will develop test specifications, encourage third party tool development, and conduct test activities that allow vendors to test their implementations.
OMA has a number of technical working groups for developing mobile services enabler specifications. Among these working groups, the OMA Location Working Group develops Secure User Plane Location (SUPL), which employs user plane data bearers for transferring location assistance information such as GPS assistance data, and for carrying positioning technology-related protocols between mobile terminal and the network.
In OMA SUPL specification, SUPL network is an access network which facilitates the Location determination functionality and provides the SUPL bearer for a SUPL Enabled Terminal (SET) to communicate with. The SET is a logical entity in a device capable of communicating with the SUPL network, to perform a SUPL service with a SUPL Location Platform (SLP). Examples of such SET could be a UE in Universal Mobile Telecommunications System (UMTS) or Long-Tern Evolution (LTE), a MS in Global System for Mobile Communications (GSM) or Interim Standard 95 (IS-95), or a PC over an IP-based transport. The SUPL Location Platform (SLP) is an entity responsible for SUPL Service Management and Position Determination. The SLP contains the SUPL Location Center (SLC) and SUPL Positioning Center (SPC) Functions. The SLC coordinates the operations of SUPL in the network and interacts with the SUPL Enabled Terminal (SET) over User Plane bearer, while the SPC is an entity in the SUPL network responsible for all messages and procedures required for position calculation and for the delivery of assistance data.
The first version, i.e. version 1.0, of SUPL released in Jun. 15, 2007 specifies architecture of SUPL service enabler, including context model, functional blocks, logical entities, reference points or interfaces, messages and message flows for the SUPL service enabler. Currently, SUPL has been developed to version 3.0. In version 3.0 of SUPL, several services are added. One of the services is 3rd party relative location, where a SET can request for obtaining location information of another SET. However, in the 3rd party relative location service, the SET obtains only one location information at one time of another SET. Though a SET can initiate multiple positioning sessions for obtaining multiple location information at different times of another SET, such method is inefficient, and wastes network and radio sources.